Small Island is a novel divided into monologues. Its arrangement of different points of view is reminiscent of other novels structured in this way: Julian Barnes's Talking It Over and Love, etc, Graham Swift's Last Orders, or Nick Hornby's A Long Way Down. In all these, the heading of each chapter gives the name of the speaker.

The technique was pioneered by a modernist classic: William Faulkner's As I Lay Dying. Virginia Woolf used it – in a manner that turned narration into a form of introspection – in The Waves. It is a good example of a narrative technique that might once have been disconcertingly experimental but has become mainstream.

One readily calls each narrator a "speaker": Levy has chosen to distinguish one from another through different uses of language that we associate with speech. This is technique common in novels divided into monologues (some of the narrators in Faulkner's original are obscurely demotic).

Gilbert's monologues preserve some of the habits of Jamaican dialect. "Cha! Would you believe the gas choose that moment to run out." Hortense, schooled in Wordsworth and elocution back in Jamaica, is disappointed that Gilbert lacks "breeding" and strives for some kind of hauteur in her monologues. "I did not wish him to stand before me in his nakedness as puffed as a peacock." She flourishes her educated diction ("perused", "forbearance") while tripping into colloquial phrases ("Mrs Bligh stare on me", "an educated woman such as I").

So narrative prose is on a level with dialogue in the novel. This is also the case for the two white English narrators, Queenie and Bernard, a husband and wife estranged by war and by Queenie's realisation that she has married only in order to escape from her family.

Queenie narrates with the exclamations and self-interruptions that we recognise from speech. "I bet he did." "Why not?" "I knew that, but blinking heck!" A butcher's daughter, she's had elocution lessons that produce clashes of register in her monologues (she is capable of phrases such as "my errant husband" and "the motley mixture").

Bernard has a stranger idiolect, distinguished by sentences stripped of verbs or pronouns, reduced to fury. "Murdering thugs would strangle their own mother for money. Shoot us, run us through, and not the first to go up in smoke. Worse than the Japs. All us chaps knew it. Bloody coolies."

Colloquialism signals the informality of narration: the characters may be trying to justify themselves, but they are telling the reader what they think rather than what they are able to say to each other. Novels narrated in the third person frequently shift between the points of view of different characters, but the novel in monologues goes further: it segregates points of view. The reader knows that in any given chapter he or she will see the world through the eyes of just one character. It is a narrative method calculated to let us hear how a point of view becomes a prejudice.

They are also sealed off from each other because they have secrets. Some of these are harmless. When Hortense comes to love Gilbert, the man she has married merely in order to secure entry to England, she knows that it would do no good to reveal that Michael Roberts was not her brother but her distant cousin – and that her love for him was certainly not that of a sister.

Others are shameful. After the war has ended, Bernard fails to return to Queenie for two years because he is convinced that he has contracted syphilis while serving in India, but he will never tell her this.

The different narrators cannot hear each other's narrations, yet they do oddly cooperate in the building of the whole narrative. In the sections of the novel describing events in 1948, one will pick up the story at the point where the preceding narrator has left it. This dovetailing is a convention of the narrative form.

Are some of the monologists more reliable than others? Levy has taken two important decisions that peculiarly influence our likely answers to this question. First, she has given a prologue to Queenie, who recounts her visit as a child to the 1924 British Empire Exhibition in London, a would-be celebration of imperial dominance. She describes her first encounter there with a black person. In the novel that follows, Queenie does not "speak" again for more than 100 pages, but we know in advance that her deeply ambivalent feelings about black men and women will be central to the story.

Second, Levy has decided to have the sections of the novel dealing with the events of 1948 narrated by three of the novel's four narrators: Bernard is excluded. He gets the chance to describe his traumatic wartime experiences, but he is denied a voice in the present. His bitterness and racism get their life from the past.

John Mullan is professor of English at University College London. Join him and Andrea Levy for a discussion on Monday 24 January at 7pm, Hall One, Kings Place, 90 York Way, London N1 9AG. Tickets: £9.50 online or £11.50 from the box office: 020 7520 1490.